How does depolarization and repolarization occur?

As a subject matter expert in cellular physiology, I can explain the processes of depolarization and repolarization in the context of an action potential, which is a rapid and temporary change in the membrane potential of a cell. Depolarization is the initial phase of an action potential where the cell's resting membrane potential, which is typically polarized (negative inside, positive outside), becomes less negative or even positive. This occurs due to the opening of voltage-gated sodium channels in the cell membrane. When a stimulus is strong enough to reach the threshold potential, these channels open, allowing an influx of sodium ions (Na+) into the cell. The inflow of positive charge makes the inside of the cell more positive, causing depolarization. Repolarization follows depolarization and is the process by which the cell returns to its resting membrane potential. After depolarization, voltage-gated potassium channels open, allowing potassium ions (K+) to flow out of the cell. This outflow of positive charge helps to re-establish the negative charge inside the cell. Additionally, the sodium channels close, preventing further influx of sodium ions. The combination of these two events brings the membrane potential back to its resting state. Here's the translation of the above explanation into Chinese: 作为细胞生理学领域的专家，我可以解释动作电位中的去极化和复极化过程。动作电位是细胞膜电位的快速且暂时的变化。 去极化 是动作电位的初始阶段，细胞的静息膜电位通常为极化状态（内部负，外部正），在这个阶段变得不那么负或者甚至变为正。这是由于细胞膜上的电压门控钠通道打开。当刺激足够强以至于达到阈值电位时，这些通道打开，允许钠离子（Na+）流入细胞内。正电荷的流入使细胞内部变得更正，导致去极化。 复极化 是去极化之后的阶段，是细胞返回其静息膜电位的过程。去极化后，电压门控钾通道打开，允许钾离子（K+）流出细胞外。这种正电荷的流出有助于重新建立细胞内部的负电荷。此外，钠通道关闭，阻止了钠离子的进一步流入。这两个事件的结合使膜电位恢复到其静息状态。

In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential. ... The opposite of a depolarization is called a hyperpolarization.